1. Field of the Invention
The present invention relates to a multi-strobe apparatus for generating multi-strobe having a plurality of strobes, a testing apparatus for testing an electronic device, and an adjusting method for adjusting a timing of generating a strobe of each strobe of the multi-strobe. More particularly, the present invention relates to a multi-strobe apparatus for controlling a timing of generating each strobe.
2. Description of Related Art
Conventionally, in case of detecting a variation point of a value of a signal to be measured, one strobe is delayed at every cycle of the signal to be measured and is output, the value of the signal to be measured is detected for each strobe, and variation in the value is detected. This method is used to detect a variation point of the value of each of a data signal and a DSQ signal, etc. for a memory setup/hold testing, for example.
A device of double data rate type which outputs a data signal synchronously with a rising or a falling of a clock (DQS) like DDR-SDRAM (Double Data Rate-SDRAM), for example, makes the data signal follow up the clock for every predetermined width of the output data and outputs the data signal. Thus, a timing condition of setup/hold for data transfer is relieved. This kind of device is required to have a predetermined setup time and a predetermined hold time between the data signal and the clock in order to perform reset/hold of data without fault.
Conventionally, each of the values of the data signal and the clock is detected by one strobe and a variation point of each value is detected. Then, pass/fail of a device under test (“DUT”) is determined according to whether or not the detected variation point satisfies the predetermined setup time and the predetermined hold time.
However, since each of the values of the data signal and the DSQ is detected at every cycle of each signal by one strobe, it is impossible to perform the testing accurately in case a jitter is generated in the data signal and the DSQ due to various causes such as power supply variation and heat variation of the device. Further, since the data signal and the DSQ are scanned by one strobe, it takes much time to perform the testing.
Accordingly, it is an object of the present invention to provide a multi-strobe apparatus, a testing apparatus, and an adjusting method, which are capable of overcoming the above drawbacks accompanying the conventional art. The above object can be achieved by combinations described in the independent claims. The dependent claims define further advantageous and exemplary combinations of the present invention.